[Linux-ia64] 2.3.99-pre5 Kernel Compile

[Linux-ia64] 2.3.99-pre5 Kernel Compile

[roneng]

Hi,

I was wondering if anyone has had a problem with very large kernel sizes
when
compiling the 2.3.99-pre5 kernel with the 4/24 patch.
When I compile this kernel I get a 34Mb kernel, but when I compile the
 2.3.47 kernel sources in turbolinux distribution with the same .config
file
I get a 5MB kernel. The toolchains I have tries have been the 2/16
toolchain
included with the turbolinux distribution and the 3/23 toolchain (
gnupro-2.9-000323.src.rpm).


Thank you,
Ronen Grosman
- e-mail roneng@ca.ibm.com

Re: [Linux-ia64] 2.3.99-pre5 Kernel Compile

[Don Dugger]

Ronen-

Remove the `-g' flag from the `CFLAGS' definition in your top level
`Makefile' and your kernel should go back to ~5M.

On Wed, Apr 26, 2000 at 10:40:02AM -0400, roneng@ca.ibm.com wrote:
> 
> 
> Hi,
> 
> I was wondering if anyone has had a problem with very large kernel sizes
> when
> compiling the 2.3.99-pre5 kernel with the 4/24 patch.
> When I compile this kernel I get a 34Mb kernel, but when I compile the
>  2.3.47 kernel sources in turbolinux distribution with the same .config
> file
> I get a 5MB kernel. The toolchains I have tries have been the 2/16
> toolchain
> included with the turbolinux distribution and the 3/23 toolchain (
> gnupro-2.9-000323.src.rpm).
> 
> 
> Thank you,
> Ronen Grosman
> - e-mail roneng@ca.ibm.com
> 
> 
> 
> 
> _______________________________________________
> Linux-IA64 mailing list
> Linux-IA64@linuxia64.org
> http://lists.linuxia64.org/lists/listinfo/linux-ia64

-- 
Don Dugger
"Censeo Toto nos in Kansa esse decisse." - D. Gale
n0ano@valinux.com
Ph: 303/938-9838

Re: [Linux-ia64] 2.3.99-pre5 Kernel Compile

[David Mosberger]

Alternatively, strip the debug info with "strip" or "objcopy
--strip-all".  The debug info is quite useful when you need to map
kernel addresses to source code (gdb does that very well).

Perhaps the real question should be: why is it that gcc produces such
bloated debug info?  I'm not 100% sure, but I do believe that it would
be possible to do a lot better (perhaps with help from the linker).

	--david

>>>>> On Wed, 26 Apr 2000 08:47:47 -0600, Don Dugger <n0ano@valinux.com> said:

  Don> Ronen- Remove the `-g' flag from the `CFLAGS' definition in
  Don> your top level `Makefile' and your kernel should go back to
  Don> ~5M.

  Don> On Wed, Apr 26, 2000 at 10:40:02AM -0400, roneng@ca.ibm.com
  Don> wrote:
  >> 
  >> 
  >> Hi,
  >> 
  >> I was wondering if anyone has had a problem with very large
  >> kernel sizes when compiling the 2.3.99-pre5 kernel with the 4/24
  >> patch.  When I compile this kernel I get a 34Mb kernel, but when
  >> I compile the 2.3.47 kernel sources in turbolinux distribution
  >> with the same .config file I get a 5MB kernel. The toolchains I
  >> have tries have been the 2/16 toolchain included with the
  >> turbolinux distribution and the 3/23 toolchain (
  >> gnupro-2.9-000323.src.rpm).
  >> 
  >> 
  >> Thank you, Ronen Grosman - e-mail roneng@ca.ibm.com
  >> 
  >> 
  >> 
  >> 
  >> _______________________________________________ Linux-IA64
  >> mailing list Linux-IA64@linuxia64.org
  >> http://lists.linuxia64.org/lists/listinfo/linux-ia64

  Don> -- Don Dugger "Censeo Toto nos in Kansa esse decisse." -
  Don> D. Gale n0ano@valinux.com Ph: 303/938-9838


  Don> _______________________________________________ Linux-IA64
  Don> mailing list Linux-IA64@linuxia64.org
  Don> http://lists.linuxia64.org/lists/listinfo/linux-ia64

Re: [Linux-ia64] 2.3.99-pre5 Kernel Compile

[Jim Wilson]

	Perhaps the real question should be: why is it that gcc produces such
	bloated debug info?

I haven't looked at the ia64-linux kernel specifically, but in most cases the
problem is duplicated debug info for header files.  This is particularly a
problem for large C++ programs.  If a header file is included in twenty
different files, you end up with 20 copies of the debug info for that
header file.  This is something that everyone using DWARF2 eventually
complains about.  There are also a few other areas where the gcc DWARF2
implementation could be improved with respect to debug info size.

It is possible to eliminate a lot of the duplicate info in the linker.
However, because DWARF2 debug info is highly encoded to save space, this
would require the linker to decode the debug info, factor out common info,
and then re-encode the debug info.  This is a lot of work for the linker, and
is not easy to implement.

There is a DWARF2 standards committee that is working on a revision of the
DWARF2 standard, and one of the things that they are working on making it
easier to reduce the debug info size at link time.  If we could put header
file debug info in its own section for instance, then we can use normal linker
support for discarding duplicate sections to reduce the debug info size.
Cygnus is contributing to this committee, and I expect that we will be
implementing some of these new features in the gcc DWARF2 implementation.

People using stabs don't see this problem because stabs already has support
for eliminating duplicate header file debug info.  This is easy to do in
stabs, because there is no complicated encoding of the data that gets in the
way of identifying duplicate debug info.

Jim